Polysaccharide diversity in VNI isolates of Cryptococcus neoformans from Roraima, Northern Brazil

Polysaccharide diversity in VNI isolates of Cryptococcus neoformans from Roraima, Northern Brazil

Species of the Cryptococcus genus comprise environmental, encapsulated fungal pathogens that cause lethal meningitis in immunosuppressed individuals. In humans, fungal uptake of hypocapsular Cryptococcus by macrophages was associated with high fungal burden in the cerebrospinal fluid and long-term p...

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Bibliographic Details
Published in:Fungal biology Vol. 123; no. 10; pp. 699 - 708
Main Authors: Dal Pupo, Halan D., Sena, Bianca A.G., Reis, Flavia C.G., Machado, Lumena, Fortes, Silvana T., de Almeida Junior, João N., Godinho, Rodrigo M.C., Rodrigues, Marcio L.
Format: Journal Article
Language:English
Published: Netherlands Elsevier Ltd 01-10-2019
Subjects:
Animals
Brazil
Capsule
Columbidae - microbiology
Cryptococcal diversity
Cryptococcosis - microbiology
Cryptococcosis - transmission
Cryptococcus neoformans - chemistry
Cryptococcus neoformans - growth & development
Cryptococcus neoformans - isolation & purification
Cryptococcus neoformans - metabolism
Feces - microbiology
Glucuronoxylomannan
Glycan heterogeneity
Humans
Polysaccharides - chemistry
Polysaccharides - metabolism
Brazil
Cryptococcal diversity
Glucuronoxylomannan
Capsule
Glycan heterogeneity
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Summary:Species of the Cryptococcus genus comprise environmental, encapsulated fungal pathogens that cause lethal meningitis in immunosuppressed individuals. In humans, fungal uptake of hypocapsular Cryptococcus by macrophages was associated with high fungal burden in the cerebrospinal fluid and long-term patient survival. On the basis of the key role of the cryptococcal capsule in disease, we analyzed the diversity of capsular structures in 23 isolates from pigeon excreta collected in the cities of Boa Vista, Bonfim and Pacaraima, in the state of Roraima (Northern Brazil). All isolates were identified as Cryptococcus neoformans (VNI genotype) by MALDI-TOF mass spectrometry. Through a combination of fluorescence microscopy, flow cytometry, ELISA and spectrophotometric methods, each isolate was characterized at the phenotypical level, which included measurements of growth rates at 30 and 37 °C, pigmentation, cell body size, capsular dimensions, serological reactivity, urease production and ability to produce extracellular glucuronoxylomannan (GXM), the main capsular component of C. neoformans. With the exception of melanization, a formidable diversity was observed considering all parameters tested in our study. Of note, hyper and hypo producers of GXM were identified, in addition to isolates with hyper and hypo profiles of reactivity with a polysaccharide-binding monoclonal antibody. Capsular dimensions were also highly variable in the collection of isolates. Extracellular GXM production correlated positively with capsular dimensions, urease activity and cell size. Unexpectedly, GXM concentrations did not correlate with serological reactivity with the cryptococcal capsule. These results reveal a high diversity in the ability of environmental C. neoformans to produce capsular components, which might impact the outcome of human cryptococcosis.
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ISSN:1878-6146
1878-6162
DOI:10.1016/j.funbio.2019.06.003